F9 1549 then DL 2398 at Atlanta
Jacksonville → Atlanta → New York JFK
Timetable, Atlanta time
20:31F9 1549 from Jacksonville at the gate
15:16DL 2398 to New York JFK leaves the gate
18 h 45 apart on the timetable, overnight
DL 2398 leaves 18 h 45 after F9 1549 arrives on the timetable: more than half a day, so not a connection we count.